The invention relates to fluid distribution valves of the type which sequentially open a plurality of outlet ports of a closed chamber that receives pressurized fluid via an inlet port, and more particularly to an improved distribution valve having a high efficiency impeller, gear assembly, a sequential valve actuation mechanism, and a dual cam mechanism adapted to prevent undesired excursions of valve balls when they are supposed to remain seated.
Multi-outlet fluid distribution valves that receive fluid under high pressure through an inlet port and distribute the fluid, one port at a time, through sequential outlet ports are commonly used in self-cleaning swimming pool systems. In such systems, swimming pool water is pumped at high pressure, typically roughly twenty to forty pounds per square inch, into the inlet port of the distribution valve. The outlet ports are coupled by lengths of PVC pipe to spaced "cleaning heads" that are installed in the bottom of the swimming pool surface and eject rotary jets of high pressure water along the bottom of the pool to effectively "sweep" circular areas around each cleaning head. For example, a fluid distribution valve somewhat similar to the one disclosed in U.S. Pat. No. 3,405,773, issued to K. W. Hansen on Oct. 15, 1968 and assigned to the present assignee, has been proposed. However, experience in the swimming pool industry has indicated that there is a need for a further improved implementation of the subject distribution valve. Chemicals commonly used in swimming pool water have been found to gradually weaken and degrade some of the plastic and metal components that have been used in prior distribution valves. Some of the prior distribution valves have not been reliable in the presence of substantial variations in the inlet pressure, or at low water flow rates. In some cases, build-up of debris on some of the components of prior distribution valves has interfered with their proper operation, increasing maintenance costs, especially when the chemical balance of the swimming pool water has not been properly maintained.
The distribution valve described and claimed in the above-identified parent application, and also described herein with reference to FIGS. 1-5, solved many of the problems of earlier fluid distribution valves.
However, one problem, an intermittent one, that has been found to occur with the distribution valve of FIGS. 1-5 is that in certain installations, the momentum of water in pipes connected between the fluid outlet port and cleaning heads disposed on the bottom surface of a swimming pool apparently causes vacuum conditions in those lines as the ball valves become seated, producing a reversal of forces on the fluid in the lines and reversing the momentum of the fluid. This causes the ball valves to then become unseated. In some instances, this sequence of events would occur in a continuous oscillatory manner, causing an undesirable, noisy, stress-producing "hammering" of the ball onto and off of its seat when the ball actually was supposed to remain seated, i.e., closed.
Several techniques for solving this problem have been investigated by us, including provision of check valves under each ball, and providing means for letting a small amount of air into the lines in response to the occurrence of a vacuum produced by momentum of fluid in the line connected to the fluid outlet port of the distribution valve. These techniques have been found to be unsatisfactory.
Thus, there remains a need for a further improvement of the distribution valve described and claimed in the above-identified parent application to prevent undesired oscillatory or repetitive "hammering" of ball valves that should be seated, as a result of momentum reversals of fluid in the outlet lines.
Accordingly, it is an object of the invention to provide an improved distribution valve that operates reliably at low inlet pressures and low fluid rates, is more resistant to degradation caused by swimming pool chemicals, and requires less maintenance than prior distribution valves.
It is another object of the invention to provide an improved distribution valve that prevents repetitive "hammering" or partial opening and closing of ball valves in the improved distribution valve as a result of momentum reversals of fluid in outlet lines connected to outlet ports of the distribution valve.